Method for lining firearm barrels



Nov. 14, 1967 J, F. WELLE R 3,351,994

METHOD FOR LINING FIREARM BARRELS Filed Aug. 19, 1966 FIG-.1

' INVENTOR.

JAMES F. WELLER "/K//. M FIGJ. M

United States Patent 3,351,994 METHOD FOR LINING FIREARM BARRELS James F. Weller, Bloomfield, Ind., assignor to the United States of America as represented by the Secretary of the Navy Filed Aug. 19, 1966, Ser. No. 574,285 2 Claims. (Cl. 29-1.1)

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to liners for firearm barrels and more particularly to a method for securing a liner to a firearm barrel.

Presently the United States military departments have a very large number of 30-caliber weapons, such as M-l rifles, Browning automatic rifles and machine guns that are being converted to use 7.62 mm. NATO ammunition. In order to accommodate the smaller cartridge of the NATO ammunition, it is necessary to put a sleeve or liner in the firearm barrel of the weapon to be converted.

While various types of firearm barrel liners and methods for securing liners to firearm barrels are known in the art, all heretofore known methods of securing liners to firearms barrels have proven to be either impractical or too costly. One of the means commonly employed for securing a liner to a firearm barrel is by threads. This entails providing threads on both the liner and in the barrel and is a relatively costly method. As it is probable that several hundred thousand weapons will be converted, a small savings on each weapon will result in a large dollar savings.

Other means for securing a liner to a firearm barrel includes the use of pins or screws, or a combination of both. Experience has shown, however, that the use of pins or screws has proven unsatisfactory for the reason that the torque forces transmitted to the barrel liner are of such a high order that the securing means are entirely inadequate to hold the liner in place without subsequent displacement after a somewhat limited use of the firearm barrel.

The present invention relates to a method for securing a liner to a firearm barrel which is not only relatively inexpensive, but repeated tests have proven that the liner is firmly locked or secured to the firearm barrel. A spiral or helical groove is first cut into the inside circumference of the barrel in the region where the liner is to be located. Next, a liner is inserted into the barrel and then a high powered cartridge is placed in the barrel and fired. The force of the resultant explosion causes the liner to be forced into the groove cut into the barrel and the liner becomes firmly locked in place.

It is therefore a general object of the present invention to provide an improved method for modifying a military weapon so that it will accommodate smaller size ammunition.

Another object of the present invention is to provide an improved method for securing a liner to a firearm barrel whereby the liner is securely attached thereto.

Other objects and advantages of the present invention will be readily appreciated as the same becomes better Patented Nov. 14, 1967 understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIGURE 1 is a partial sectional view showing a firearm barrel having an internal groove therein;

FIGURE 2 is a partial sectional view showing a firearm barrel having a liner therein; and

FIGURE 3 is an enlarged partial sectional view showing a liner locked into a groove.

Referring now to the drawing, there is shown a firearm barrel 11, which by way of example, might be a barrel of the type used on an M-l rifle by the various military departments. Barrel 11 is comprised of a muzzle part 12 having rifiings 13 therein and a breech part 14, which includes a cartridge chamber 15. At the forward end of cartridge chamber 15, a helical groove 16 is cut therein. By way of example, groove 16 might be a 60 Vgroove of a depth of about 0.005 inch and cut with a helical lead of 18 turns per inch.

A liner 17, having an outer configuration that conforms to the configuration of a cartridge chamber 15, is inserted into chamber 15 and the forward end of liner 17 is adjacent groove 16. In the event that the firearm barrel was removed from the remainder of the weapon in order to facilitate the machining of groove 16 and the installation of liner 17, the weapon is then assembled and a high powered cartridge is loaded into chamber 15 and fired. As shown in FIGURE 3 of the drawing, the re-- sultant explosion due to the firing of the high powered cartridge causes a portion of metal on the outer periphery of liner 17 to be forced into the various convolutions of groove 16. Thus the liner 17 becomes firmly locked to barrel 11.

-It can thus be seen that the present invention provides an improved method for modifying a firearm barrel so that it will accommodate a smaller size cartridge. Obviously many modifications and variations of the present invention are possible in the light of the above teachings. For example, while the configuration of groove 16 is a helix, groove 16 was cut in this manner due to its ease of manufacture, however, grooves of other configurations would also provide a locking feature for securing liner 17 to the barrel. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A method of chambering a firearm barrel for accommodating a smaller size cartridge comprising:

first cutting a groove in a chamber of a firearm barrel,

then placing a liner in said chamber such that a portion of said liner is adjacent said groove, and

then firing a high powered cartridge in said firearm barrel whereby said liner becomes securely locked to said firearm barrel by engagement with said groove.

2. A method of chambering a firearm barrel as set forth in claim 1 wherein said step of first cutting a groove comprises cutting a V-shaped helical groove in a chamber of a firearm barrel.

No references cited.

RICHARD H. EANES, JR., Primary Examiner. 

1. A METHOD OF CHAMBERING A FIREARM BARREL FOR ACCOMMODATING A SMALLER SIZE CARTRIDGE COMPRISING: FIRST CUTTING A GROOVE IN A CHAMBER OF A FIREARM BARREL, THEN PLACING A LINER IN SAID CHAMBER SUCH THAT A PORTION OF SAID LINER IS ADJACENT SAID GROOVE, AND THEN FIRING A HIGH POWERED CARTRIDGE IN SAID FIREARM BARREL WHEREBY SAID LINER BECOMES SECURELY LOCKED TO SAID FIREARM BARREL BY ENGAGEMENT WITH SAID GROOVE. 